Al Williams

Dr. Dobb's Bloggers

The $25 FPGA

September 16, 2013

I've long been an advocate for getting people started using FPGAs.

I've long been an advocate for getting people started using FPGAs. I've mentioned here before that FPGAs aren't for everything (no tool is for everything), but I do often see people struggling to build something with a CPU that would be pretty easy to do with an FPGA if they only knew how.

When FPGAs were first on the market, it was a pretty major investment in hardware and software to get going with them. Things have certainly changed. Most vendors have adequate free tools for their silicon, so the cost of software (at least, considering that you surely already have a computer running some sort of operating system) is nil. Development boards keep getting cheaper and the interface between the PC and the FPGA doesn't have to be very expensive either.

In fact, some development boards have dedicated PC ports (usually USB). The board can use the port to configure the FPGA on the fly, burn the onboard configuration flash (which makes the design semi-permanent; that is, it "sticks" until you reflash it), and possibly even do some debugging.

However, Lattice seems to have taken this idea to the extreme. The iCEstick evaluation kit looks like a naked USB memory stick. Onboard is a fairly small FPGA, a USB interface chip, an IrDA transceiver, an oscillator, and a 32-megabit flash memory. There are also 5 LEDs, 16 digital I/O pins, and a PMOD port that can connect to many off-the-shelf modules from Digilent and a few other vendors.

The cost? $25. The FPGA isn't going to host the next supercomputer. It has 1,280 logic cells, a PLL for clock generation, and a modest amount of RAM blocks (64 kbits). On the other hand, the chip draws very little current, which is attractive in many applications. While 1280 logic cells doesn't sound like a lot compared to some of the big chips, it is a lot more than, say, a common CPLD, and you can do quite a bit with those.

The iCEcube2 software allows you to work with the device on Windows or Linux. These would be great for classroom use or for self-study. Most people drop more money on a week's worth of premium coffee (not me; I gave it up years ago). I plan on getting a few of these because I frequently loan FPGA boards out and at that price I won't be so worried about getting them back. Look for my thoughts on actually using the iCEstick later this year.

What's your favorite FPGA development board? I'm partial to the Digilent Spartan 3 board but I agree it is getting a bit dated. Leave a comment about what boards you are using and why.

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